Excellent question, this is up there with 'How to select a tripod?', and just like with that question, if in the long run you actually use the light meter, you're going to wind up upgrading/sidegrading several times to find exactly what you want :)
tl;dr: If you're metering large scenes such that you can't stand next to the entirety of your subject, you likely want a narrow (1-3 degree) spot meter that allows you to look through the spotmeter at your subject using reflective metering. Don't buy a meter just to replace a broken meter in your old film camera, do buy a meter to gain greater control/mastery of the exposure of your photos, or because your camera has no meter :)
First you need to consider what you plan on generally shooting, let's broadly break that into two camps:
- your subject is close and you can meter it using incidence metering
- your subject is far away or vast and you need to use reflective metering.
(I notice you didn't mention reflective/incidence metering in your list of differences, it's certainly something to consider, Sekonic has a good article on it).
Examples of the first case would be studio, macro or portrait photography and examples of the second case would be landscape or architecture photography (though there are many more examples and they do cross over).
If you plan on mostly photography the first type, you're going to be very interested in incidence metering: holding the meter at the subject and metering the light that is actually hitting the subject. Incidence metering is more accurate than reflective metering as its not impacted by things like subject color/texture and you can angle the meter at different light sources etc, the downside is you have to be at your subject :)
If you plan on mostly photography of the second type, you're going to be very interested in reflective metering (spot metering in particular): pointing the meter at parts of your subject and metering the light that is reflected off the subject. Reflective metering can be challenging since it's affected by color/texture (metering a black, white or green subject in the same lighting condition will give different results) but it allows you to meter vast subjects easily.
It sounds like you're primarily interested in the second case so let's focus on that.
The way in which your meter is going to really help you photograph a large scene is by figuring out all the items you want in your frame, metering each one individually (using the spot meter functionality), looking at all the resulting values and picking camera settings that will expose the components of your scene the way you want them. This could be a landscape with a house, a tree, hills and the sky that you want to consider; or a single tree with a person under it and you want to make sure all the highlights and shadows are exposed correctly. If this sounds like The Zone System that's because it is, but don't go get overwhelmed by the zillions of pages of info available on it (since a lot of The Zone System is about development). Just consider a simplified version where there are exposure 'zones' that you're trying to fit into the exposure latitude of your film/sensor.
So how do you pick a meter for this? At a basic level, the most important thing is you want a meter that has a narrow spot (1 degree is great!) that lets you look through the meter at the surfaces you're interested in. A nice new digital Sekonic will let you meter off multiple surfaces and then you can look at the display and it'll show you all the values you just recorded so you can see the exposure latitude and adjust ISO/Shutter/Aperture to see where different settings fall in that exposure latitude. But even an older spot meter (Pentax Digital Spotmeter for instance, which is awesome) will give you EV values that you can quickly dial in different camera settings to see what exposure latitude you have, its less slick but can actually be quicker. I have both a Sekonic L-758 and a Pentax digital spot V and often pick the Pentax over the Sekonic.
If you get a meter with a wider spot (5 degrees as you mention) or one that doesn't have a spot, or doesn't let you look through the viewfinder at the spot it will be harder to be sure you're accurately metering what you think you're metering.
All the other things you mention are also important but are features that should be easy to consider since either you need them or don't (like flash support) or they're nice-to-haves (body calibration).
